High performance conventional radio designs incorporate optimized individual circuit components which are formed from different manufacturing processes. Among these components are gallium-arsenide-based power amplifiers (PAs) and transmit/receive (T/R) switches, ceramic-based RF filters, high-temperature ceramic-based baluns, lithium tantalate-based surface-acoustic-wave filters, crystal (XTAL) oscillators and digital physical-layer (PHY) chips that are all based on different material structures. For example, FIG. 1 shows a traditional prior art hybrid radio chip including a plurality of chips which are needed to realize the radio.
The drive to maximize radio performance generally leads to this type of hybrid multichip solution. However, hybrids result in high cost due to assembly, degraded reliability and increased power consumption mainly resulting from interconnection of the various circuit components, as compared to a hypothetical single chip radio. In addition to the above mentioned shortcomings of the hybrid radio approach, the hybrid approach necessarily produces a radio having a large footprint.
The realization of a practical fully integrated single chip radio has not seriously been considered until recently primarily because of the frequency limitations of the transistors combined with the required size of antenna structures to process these frequency limited signals. For example, transistors having ft values of about 10 GHz will generally permit RF circuit operation up to about 2.4 GHz. At 2.4 GHz the free space wavelength is 125 mm. Thus, on chip integration of a conventional resonant antenna, such as a half wave or quarter wave antenna, is clearly not practical as the chip would require dimensions of about 62.5, or 31.25 mm, respectively.
Using 2-mm long integrated antennas, wireless communication from one side of an IC to its other side at 15 GHz has been demonstrated by a group including the inventor using a 180 nm CMOS process [B. Floyd, C. M. Hung, and K. K. O, “15 GHz Wireless Interconnect Implemented in a 0.18-μm CMOS Technology Using Integrated Transmitters, Receivers, and Antennas,” 2001 VLSI Symposium on Circuits, pp. 155–158, Kyoto, Japan, June 2001]. Furthermore, the inventor also participated in recent demonstrations of a 26 GHz tuned amplifier using 100 nm MOS transistors [B. Floyd, L. Shi, Y. Taur, I. Lagnado, and K. K. O, “A 23.8-GHz SOI Tuned Amplifier,” IEEE Trans. On MTTS, vol. 50, issue 9, pp 2193–2196, September 2002 and 26 GHz and 50 GHz voltage controlled oscillators (VCO) [C. M. Hung, L. Shi, I. Lagnado, and K. K. O, “A 25.9-GHz Voltage-Controlled Oscillator Fabricated in a CMOS Process,” 2000 VLSI Symposium on Circuits, pp. 100–101, Honolulu, Hi., June 2000], [H. M. Wang, “A 50-GHz VCO in 0.25 μm CMOS,” Tech. Digest of 2001 International Solid State Circuits Conference, San Francisco, Calif., February 2001] in CMOS technologies. These demonstrations suggest that current CMOS technologies are starting to be capable of supporting RF circuits operating at 10 GHz and higher.
However, sufficiently fast transistors, amplifiers and oscillators alone are not sufficient to realize practical single chip radios. For example, any one the following challenges can limit the performance and prevent practical realization of a true single chip radio:                1. Low breakdown voltage resulting from small feature-size technology (e.g. 100 nm CMOS transistors) required for high frequency operation.        2. Parasitic coupling principally from one device to another through the common substrate. For example, coupling between the power amplifier to other analog circuits on-chip can be substantial because of the normally high signal level. Substrate noise coupling from digital circuits through the common substrate to the on-chip antennas can also be a problem.        3. Integration of low loss filters. For example, on-chip inductors tend to be lossy and provide Q's of no more than about 5.        4. Integration of a reference crystal or other oscillator.        5. Low integrated antenna gain. The dielectric surrounding integrated antennas tend to be lossy, such as moderately to heavily doped silicon substrates.        6. Adverse passivation effects on integrated antenna performance.        7. Adverse effects of metalization associated with integrated circuits which are disposed near integrated antennas. Nearby metalization can act to modify electromagnetic fields, such as by reflection, absorption and radiation.        8. Integration of bypass capacitors having sufficient capacitance to sufficiently shunt unwanted power supply noise to ground. Long leads from a remotely located battery can require large value capacitors, the large value capacitors requiring large areas for implementation.        
In view of the many challenges noted above, it is not surprising that those in the art have generally considered the realization of a true single chip radio only a dream. Although many have referred to fabrication or design of radio subsystems as a “single-chip radio”, such systems lack one or more important components for a true single chip radio, such as on-chip antennas and/or digital circuitry, such as digital signal processors.
For example, applied to telecommunications, the term “single-chip” has been used to generally refer to a hypothetical single telecom transceiver IC which would combine the RF front-end with the DSP core of the transceiver. However, even the realization of a fully integrated single-chip transceiver has proved elusive.